Cheapest priced copy (Marvel Super Heroes Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Costume Closet 
Artifact · Uncommon · Marvel's Spider-Man · #5
This artifact enters with two +1/+1 counters on it.
{T}: Move a +1/+1 counter from this artifact onto target creature you control. Activate only as a sorcery.
Whenever a modified creature you control leaves the battlefield, put a +1/+1 counter on this artifact. (Equipment, Auras you control, and counters are modifications.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Marvel Super Heroes Commander | 770 | Uncommon | $0.35 | $0.49 |
| Marvel's Spider-Man | 5 | Uncommon | $0.35 | $0.49 |
6 rulings from Wizards of the Coast
- 19 September 2025If Costume Closet has left the battlefield or has no +1/+1 counters on it by the time its activated ability resolves, you won't put a +1/+1 counter on the target creature. If the creature becomes an illegal target or can't have a +1/+1 counter put onto it for some other reason, you won't remove a +1/+1 counter from Costume Closet.
- 19 September 2025An Aura controlled by an opponent does not cause a creature you control to be modified.
- 19 September 2025A creature that is equipped is considered modified no matter who controls the Equipment that's attached to it.
- 19 September 2025Once Costume Closet runs out of +1/+1 counters, it remains on the battlefield. However, activating its second ability won't do anything.
- 19 September 2025The +1/+1 counters on Costume Closet won't affect it unless it somehow becomes a creature.
- 19 September 2025A creature with a counter on it is considered modified no matter what kind of counter it is or which player put it on that creature.